Spectroscopic confirmation of a gravitationally lensed Lyman-break galaxy at z[C ii]= 6.827 using NOEMA

S. J. Molyneux, R. Smit, D. Schaerer, R. J. Bouwens, L. Bradley, J. A. Hodge, S. N. Longmore, S. Schouws, P. Van Der Werf, A. Zitrin, S. Phillips

Research output: Contribution to journalArticlepeer-review

Abstract

We present the spectroscopic confirmation of the brightest known gravitationally lensed Lyman-break galaxy in the Epoch of Reionization (EoR), A1703-zD1, through the detection of [C ii] 158 μm at a redshift of z = 6.8269 ± 0.0004. This source was selected behind the strong lensing cluster Abell 1703, with an intrinsic luminosity and a very blue Spitzer/Infrared Array Camera (IRAC) [3.6]-[4.5] colour, implying high equivalent width line emission of [O iii] + Hβ. [C ii] is reliably detected at 6.1σ cospatial with the rest-frame ultraviolet (UV) counterpart, showing similar spatial extent. Correcting for the lensing magnification, the [C ii] luminosity in A1703-zD1 is broadly consistent with the local L[C,II]-star formation rate (SFR) relation. We find a clear velocity gradient of 103 ± 22 km s-1 across the source that possibly indicates rotation or an ongoing merger. We furthermore present spectral scans with no detected [C ii] above 4.6σ in two unlensed Lyman-break galaxies in the Extended Groth Strip (EGS)-Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) field at z ∼6.6-6.9. This is the first time that the Northern Extended Millimeter Array (NOEMA) has been successfully used to observe [C ii] in a 'normal' star-forming galaxy at z > 6, and our results demonstrate its capability to complement the Atacama Large Millimeter/submillimeter Array (ALMA) in confirming galaxies in the EoR.

Original languageAmerican English
Pages (from-to)535-543
Number of pages9
JournalMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Volume512
Issue number1
DOIs
StatePublished - 1 May 2022

Keywords

  • galaxies: evolution
  • galaxies: formation
  • galaxies: high-redshift

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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